This program covers the long-standing development of laser microsurgical techniques that initially centered on ophthalmological applications and systems of interest in that field (pulsed carbon oxide lasers and pulsed ND:YAG slit lamp-based laser systems). Its primary focus for the last 3 years has been in cardiological plication of lasers, in particular laser angioplasty. In order to develop new laser microsurgical techniques in this new field, it was necessary to analyze a variety of laser sources and their tissue effects and the feasibility of transmission through flexible fiber tics. Excimer lasers coupled to fused silica fibers were examined, well as more conventional sources (pulsed carbon dioxide and :YAG lasers and continuous-wave argon and dye lasers). New IR laser sources have been developed (in conjunction with Naval Research Lab and Quantronix Corp.) which utilize strong water absorption and can transmitted through low-loss, cladded optical fibers. They include the first use of the Erbium:YAG laser @2.94um through zirconium fluoride optical fibers and the Thulium:YAG (Cr-doped) at 1.96-2.01um through low-OH silica optical fibers. Our collaborations with the NRL and various industry groups have led to a variety of prototype laser microsurgical systems for angioplasty studies. The collaboration with MCM Labs has led to clinical trials of peripheral and, more recently, coronary laser angioplasty using a pulsed dye laser with computer-controlled fluorescence guidance. Application of our infrared lasers (particularly the Tm:YAG and silica optical fibers) to laser angioplasty systems is proceeding with parallel development of a clinical infrared version of the fluorescence guidance system and a new intravascular ultrasound/laser catheter.